Referring to FIG. 8, an example of typical industrial gas turbine engine 10 is illustrated and generally includes a compressor section 12, a combustor section 14, a turbine section 16 and an exhaust section 18. The compressor section 12 includes alternating stationary and rotating components comprising stationary vanes 20 supported to an outer compressor casing 24, and rotating blades 22 supported to a rotor assembly 26 that extends up to a location in or adjacent to the exhaust section 18 where the rear end of the rotor assembly 26 may be supported at a rear bearing 19 positioned in a rear bearing housing 21. Also, the turbine section 16 includes alternating stationary and rotating components comprising stationary vanes 28 supported to an outer turbine casing 32 and rotating blades 30 supported to the rotor assembly 26. Typically, the outer compressor casing 24 may include vane carrier structure 34 supporting the stationary vanes 20, and the outer turbine casing 32 may include vane carrier structure 36 for supporting the stationary vanes 28.
The turbine engine 10 is shown as being formed as a horizontal split plane assembly. That is, the compressor casing 24 is formed of an upper half 24a and a lower half 24b that may be joined at horizontal joints defined by respective axially extending flanges 38a, 38b. Similarly, the turbine casing 32 is formed of an upper half 32a and a lower half 32b that may be joined at horizontal joints defined by respective axially extending flanges 40a, 40b. Industrial gas turbine engines are commonly formed of relatively large components, and the horizontal split plane configuration, such as is illustrated in FIG. 8, facilitates assembly, wherein the stationary components of the lower half of the engine may be assembled, the assembled rotor assembly 26 may be placed into the lower half, and the assembled upper half may be positioned on the lower half to form an axial flow path through the engine. Assembly of the rotor assembly 26 into the lower half and positioning of the upper half into association with the lower half also comprises positioning of the outer tips of the blades 20, 30 in close association with stationary seal rings 42, 44 supported to the compressor and turbine casings 24, 32, respectively, and axially positioned between vane platforms to limit axial passage of air and hot gas flows past the rotating blade tips.
The compressor section 12 can induct ambient air and can compress it. The compressed air from the compressor section 12 can enter one or more combustors 20 in the combustor section 14. The compressed air can be mixed with fuel, and the air-fuel mixture can be burned in the combustors 20 to form a hot working gas. The hot gas is routed to the turbine section 16 where it is expanded through the alternating rows of stationary vanes 28 and rotating blades 30 and used to generate power that can drive the rotor assembly 26. The expanded gas exiting the turbine section 16 can be exhausted from the engine 10 via the exhaust section 18.
Leakage between the hot gas in the hot gas flow path and a supply of cooling fluid, such as cooling air in air cavities 46 located radially inwardly from the vanes 28 and blades 30, i.e., rim or vane cavities, reduces engine performance and efficiency. Cooling air leakage from the cavities into the hot gas flow path can disrupt the flow of the hot gases and increase heat losses. Additionally, hot gas leakage into the rim/vane cavities may yield higher vane and vane platform temperatures and may result in reduced performance, and may further result in increased thermally induced deterioration of components.